The split opcode, and a test that asked to be deleted

MTBUF's opcode is three bits at 18:16 of the first word and a fourth at bit 53 - bit 21 of the second. The table read only the contiguous part, so every half-precision variant decoded as the operation it is a variant of: tbuffer_load_format_d16_x reported as tbuffer_load_format_x, differing in the one bit nobody looked at.

Encoding now carries an optional opcode_extension. One continuation rather than a list of pieces, because that covers every split this instruction set actually has.

Also corrected D105's stated reason for leaving it open. It said MTBUF was "refused in its entirety pending a resource model" - true when written, stale since MUBUF landed. The resource model exists; a typed buffer access is the same descriptor and the same addressing with a format conversion on top.

Surprises

The pinned-gap test worked exactly as designed, which was still a small surprise to watch. the_typed_buffer_variants_are_known_to_be_conflated was written as a passing test asserting the conflation existed, so that closing the gap would fail here and name the notes needing updated. It failed with that message. Kept inverted, and strengthened: it asserts the variant is its counterpart plus eight rather than merely different, because a continuation shifted to the wrong place also produces two distinct numbers.

The rule lives in three places and only one of them is Rust. classify() is reimplemented in the generators. Updating the decoder alone would have left them classifying a half-precision variant as its counterpart and emitting a second name for an opcode that already had one - caught by the name table's duplicate refusal, but only by luck of that guard existing. Changed together.

A blind text replacement ate class Sample. Replacing classify by cutting from def classify( to the next column-zero def swallowed everything between, and in one of the two files that was a class definition and a regex. It failed loudly at the next run, and the staged copy restored it byte-identically - but the lesson is that "next top-level def" is not a function boundary, and I had no reason to think it was.

The workspace does not currently build, and not because of this. orbistoun-elf has a missing import in a test module - another thread's file, mid-edit. My crates were checked directly instead: 256 tests, clean clippy.